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PubMed1994

Consistency and reliability of voice quality ratings for different types of speech fragments.

This study describes a perception experiment in which listeners were asked to rate voice fragments obtained from a variety of speakers on grade, breathiness, and roughness. Four different types of stimuli were presented to each listener. One type of stimulus was based on connected speech fragments; the other three were based on different segments of a sustained vowel, yielding a 200 msec vowel onset stimulus, a 200 msec post-onset stimulus, and a 1000 msec whole vowel stimulus. Analyses focused on the consistency and reliability of grade, roughness, and breathiness ratings. Results indicated that stimulus type had virtually no effect on either within- or between-listener consistency of the grade, breathiness, or roughness ratings. Rating reliability too was hardly influenced by stimulus type. When determined as a function of the overall degree of deviance of a voice, the reliability of breathiness and roughness ratings was slightly higher for whole vowel and vowel onset stimuli than for connected speech and post-onset stimuli. It is concluded that connected speech stimuli are not necessarily to be preferred over vowel-type stimuli for a perceptual evaluation of grade, roughness, or breathiness. The somewhat higher reliability of ratings on vowel onset and whole vowel stimuli as compared to the post-onset stimuli is taken as an indication that the onset part of a vowel may contain voice quality cues that are less salient in the most stable part of a vowel.

Cues↗
PubMed1995

Voice intelligibility in patients who have undergone laryngectomies.

In this paper, we evaluate the speech intelligibility of two groups of Spanish-speaking people who have undergone laryngectomies: a group who used esophageal speech and a group who used tracheoesophageal (TES) prostheses. Audio recordings of 24 Spanish words produced by each talker were presented to a group of normal-hearing naive listeners who phonetically transcribed their responses. Listeners' responses were registered in confusion matrices. Results indicate that differences between these two groups of patients appear when we consider phoneme types. The difficulty in producing the voicing distinction appeared in both TES and esophageal talkers. This finding is consistent with studies of English-speaking laryngectomized patients. Considering manner of production, fricative consonants had the highest number of confusions with other phoneme class in the TES group, whereas in the esophageal group nasals resulted the highest number of confusions. However, ANOVA showed that differences between the two groups were not significant.

Humans↗
PubMed1995

Pathologic voice type and the acoustic prediction of severity.

We hypothesized that acoustic measures would predict dysphonic severity with differential results for pathological voice types. An instructional program based upon synthesized voice signals was developed to facilitate an awareness of prototypical voice types. Eighty phonatory samples representing normal subjects as well as patients with unilateral vocal fold paralysis, vocal nodules, and functional dysphonia were analyzed acoustically on the basis of four measures: average fundamental frequency (F0), jitter, shimmer, and harmonic/noise ratio (H/N ratio). Following training, 29 listeners classified 62% of the phonatory samples on the basis of breathy, hoarse, rough, and normal. Dysphonic severity of rough voices was predicted more successfully by H/N ratio (r2 = .73) than by shimmer (r2 = .43). Dysphonic severity of breathy voices was predicted only by the combined features of less jitter, more shimmer, and lower H/N ratio (r2 = .74). No combination of acoustic variables was successful in the prediction of the hoarse voice type.

Adolescent↗
PubMed1995

Variations across time in acoustic and electroglottographic measures of phonatory function in women with and without vocal nodules.

The purpose of this investigation was to identify variations over time in phonatory function of women with and without vocal nodules using acoustic and electroglottographic measures. Subjects were 10 women with vocal nodules (mean age = 22.1, range = 19-25) and 10 women with healthy larynges (mean age = 25.0, range = 18-32). Electroglottographic and audio recordings of speech were obtained for each subject over 3 consecutive days at three target times: morning, afternoon, and evening. Estimates of fundamental frequency (Hz), jitter (msec), shimmer (dB), and signal-to-noise ratio (dB) were made from a 1000 msec midportion of the vowel /a/ produced in a carrier phrase. In addition, a closed-to-open ratio was derived from the EGG duty cycle of the same 1000 msec segment and used to estimate timing characteristics of vocal fold vibration. The results showed no significant differences between the groups regarding a pattern of change in the acoustic or the EGG measures across times throughout the day. Furthermore, the experimental group demonstrated significantly lower closed-to-open ratios than the control group. With this exception, no other statistically significant differences between the groups were found.

Adolescent↗
PubMed1995

Some spectral correlates of pathological breathy and rough voice quality for different types of vowel fragments.

This study deals with the relation between listeners' ratings of pathological breathiness and roughness and certain characteristics of the voice spectrum. Two general research questions were addressed: First, which spectral parameters may serve as useful predictors of breathiness and roughness? Second, does the type of speech fragment used for analysis have an effect on the obtained regression model? Listener ratings of breathiness and roughness were obtained for three types of vowel fragments: a vowel onset segment, a mid-vowel (post-onset) segment, and a vowel segment covering the onset and the acoustically more stable post-onset parts. Results indicated that the harmonics-to-noise ratio was the best single predictor of both rated breathiness and roughness, explaining up to 54% of the true rating variance. By combining different predictors, between 75% and 80% of the breathiness variance could be explained for all three types of fragments. For roughness, a strong effect of fragment type was observed, with most variance explained in vowel onset fragments (71%), and least in post-onset fragments (52%). The effect of fragment type was also observed when regression analyses were performed with six predictors based on a factor analysis of the acoustic data.

Female↗
PubMed1995

Required number of tokens to determine representative voice perturbation values.

Acoustic perturbation analyses of prolonged vowels are used in determining phonatory stability characteristics. When a number of tokens are analyzed, the average perturbation values create a stability profile of the voice. How many tokens are needed to obtain a representative perturbation value? In this study, five perturbation measures were considered, namely, jitter, shimmer, harmonics-to-noise ratio, coefficient of variation for amplitude, and coefficient of variation for frequency. Subject groups were chosen on the basis of individual average perturbation values. Results indicate that, except for the harmonics-to-noise ratio, generally, the less stable the voice, the greater is the number of tokens needed to obtain representative averages. For highly stable voices, at least six tokens are suggested: for voices with normal to high levels of instability, at least 15 tokens are recommended. Regardless of vocal stability, at least 10 tokens are suggested for the harmonics-to-noise ratio measure.

Adult↗
PubMed1996

Acoustic correlates of breathy vocal quality: dysphonic voices and continuous speech.

In an earlier study, we evaluated the effectiveness of several acoustic measures in predicting breathiness ratings for sustained vowels spoken by nonpathological talkers who were asked to produce nonbreathy, moderately breathy, and very breathy phonation (Hillenbrand, Cleveland, & Erickson, 1994). The purpose of the present study was to extend these results to speakers with laryngeal pathologies and to conduct tests using connected speech in addition to sustained vowels. Breathiness ratings were obtained from a sustained vowel and a 12-word sentence spoken by 20 pathological and 5 nonpathological talkers. Acoustic measures were made of (a) signal periodicity, (b) first harmonic amplitude, and (c) spectral tilt. For the sustained vowels, a frequency domain measure of periodicity provided the most accurate predictions of perceived breathiness, accounting for 92% of the variance in breathiness ratings. The relative amplitude of the first harmonic and two measures of spectral tilt correlated moderately with breathiness ratings. For the sentences, both signal periodicity and spectral tilt provided accurate predictions of breathiness ratings, accounting for 70%-85% of the variance.

Adult↗
PubMed1996

Longitudinal phonatory characteristics after botulinum toxin type A injection.

Following Botulinum Toxin Type A injection, glottal competency of an adductor spasmodic dysphonia patient is thought to vary over a wide range. This study quantifies variability in laryngeal adduction for one such patient over a 10-week period. Analyses of kinematic and aerodynamic measures were used to track the voice weekly. The measures included the electroglottographic waveform width (EGGW50), nondimensional electroglottographic slope quotient (SLQ), glottal flow open quotient (FOQ), dc glottal flow, and nondimensional glottal flow peak quotient (FPQ). The results suggested that change in degree of glottal adduction over time can be observed even when vocal instability is present within each recording session. Perceptual ratings of vocal quality (breathy to pressed) were related to the laryngeal measures. The coefficient of variation for EGGW50 and the percentage of dichrotic phonations reached minima during sessions with predominantly breathy and hypoadducted phonation. The methods used in this study show potential to aid decisions about dose level and sources of perceptual adductor spasmodic dysphonia symptoms for a given patient.

Aged↗
PubMed1999

A comparison of high precision F0 extraction algorithms for sustained vowels.

Perturbation analysis of sustained vowel waveforms is used routinely in the clinical evaluation of pathological voices and in monitoring patient progress during treatment. Accurate estimation of voice fundamental frequency (F0) is essential for accurate perturbation analysis. Several algorithms have been proposed for fundamental frequency extraction. To be appropriate for clinical use, a key consideration is that an F0 extraction algorithm be robust to such extraneous factors as the presence of noise and modulations in voice frequency and amplitude that are commonly associated with the voice pathologies under study. This work examines the performance of seven F0 algorithms, based on the average magnitude difference function (AMDF), the input autocorrelation function (AC), the autocorrelation function of the center-clipped signal (ACC), the autocorrelation function of the inverse filtered signal (IFAC), the signal cepstrum (CEP), the Harmonic Product Spectrum (HPS) of the signal, and the waveform matching function (WM) respectively. These algorithms were evaluated using sustained vowel samples collected from normal and pathological subjects. The effect of background noise and of frequency and amplitude modulations on these algorithms was also investigated, using synthetic vowel waveforms.

Algorithms↗
PubMed2000

Identification of pathological voices using glottal noise measures.

We investigated the abilities of four fundamental frequency (F0)-dependent and two F0-independent measures to quantify vocal noise. Two of the F0-dependent measures were computed in the time domain, and two were computed using spectral information from the vowel. The F0-independent measures were based on the linear prediction (LP) modeling of vowel samples. Tests using a database of sustained vowel samples, collected from 53 normal and 175 pathological talkers, showed that measures based on the LP model were much superior to the other measures. A classification rate of 96.5% was achieved by a parameter that quantifies the spectral flatness of the unmodeled component of the vowel sample.

Adult↗
PubMed2000

Perception of dysphonic voice quality by naive listeners.

For clinical assessment as well as student training, there is a need for information pertaining to the perceptual dimensions of dysphonic voice. To this end, 24 naive listeners judged the similarity of 10 female and 10 male vowel samples, selected from within a narrow range of fundamental frequencies. Most of the perceptual variance for both sets of voices was associated with "degree of abnormality" as reflected by perceptual ratings as well as combined acoustic measures, based upon filtered and unfiltered signals. A second perceptual dimension for female voices was associated with high frequency noise as reflected by two acoustic measures: breathiness index (BRI) and a high-frequency power ratio. A second perceptual dimension for male voices was associated with a breathy-overtight continuum as reflected by period deviation (PDdev) and perceptual ratings of breathiness. Results are discussed in terms of perceptual training and the clinical assessment of pathological voices.

Adult↗
PubMed2000

The dysphonia severity index: an objective measure of vocal quality based on a multiparameter approach.

The vocal quality of a patient is modeled by means of a Dysphonia Severity Index (DSI), which is designed to establish an objective and quantitative correlate of the perceived vocal quality. The DSI is based on the weighted combination of the following selected set of voice measurements: highest frequency (F(0)-High in Hz), lowest intensity (I-Low in dB), maximum phonation time (MPT in s), and jitter (%). The DSI is derived from a multivariate analysis of 387 subjects with the goal of describing, purely based on objective measures, the perceived voice quality. It is constructed as DSI = 0.13 x MPT + 0.0053 x F(0)-High - 0.26 x I-Low - 1.18 x Jitter (%) + 12.4. The DSI for perceptually normal voices equals +5 and for severely dysphonic voices -5. The more negative the patient's index, the worse is his or her vocal quality. As such, the DSI is especially useful to evaluate therapeutic evolution of dysphonic patients. Additionally, there is a high correlation between the DSI and the Voice Handicap Index score.

Adolescent↗
PubMed1998

The effectiveness of voice therapy for patients with non-organic dysphonia.

Forty-five patients diagnosed as having non-organic dysphonia were assigned in rotation to one of three groups. Patients in one group received no treatment and acted as a control group. Patients in the other two groups received a programme of either 'indirect' therapy or 'direct with indirect' therapy, respectively. A self-report questionnaire of vocal performance, observed ratings of voice quality, and computer-derived acoustic measurements (signal-to-noise ratio, pitch perturbation and amplitude perturbation) were carried out on all patients before and after treatment to evaluate the changes in voice quality over time. There was a significant difference between the three groups on the self-report questionnaire, voice quality ratings and pitch perturbation measurements (P = < 0.05). Thirteen out of 15 control patients showed no significant change on any of the measures. Seven patients who received indirect treatment showed significant improvement in voice quality following treatment. Fourteen out of 15 patients who received direct treatment showed significant improvement in voice quality.

Adult↗
PubMed2000

Quality of life issues in recurrent respiratory papillomatosis.

Twenty-six adult patients attending the Royal National Throat, Nose, and Ear Hospital with Recurrent Respiratory Papillomatosis completed two postal questionnaires. One was the generic Short Form-36 (SF-36) quality of life instrument. Severely affected patients had lower scores in all dimensions of this instrument, with large differences from normal controls in dimensions of pain, physical limitation, and energy/vitality. The second questionnaire was newly devised, and designed to ask about a wide variety of larynx-specific symptoms. Answers by patients were compared with those of normal controls, and symptoms selected as significantly more likely to be reported by patients were studied further. Correlation was seen with clinical parameters, and questions likely to be responsive to clinical change in disease burden were identified.

Adolescent↗
PubMed2000

Spectral characteristics of hypernasality in maxillectomy patients.

To reveal the acoustic characteristics associated with hypernasality and to ascertain their correlation to the severity of hypernasality, 30 speech samples produced by 15 maxillectomy patients were acoustically analysed with and without an obturator prosthesis in place. The isolated, sustained Japanese vowel /i/ was used as the stimulus for acoustic measurement and perceptual judgment to evaluate the severity of hypernasality. Normalized 1/3-octave spectral analysis demonstrated the spectral characteristics of hypernasality as a rise in amplitude between the first and second formants around the 1 kHz region, and a reduction in amplitude of the frequencies higher than the second formant. High correlation was shown between the perceptual ratings and the predicted values derived from stepwise regression analysis.

Adult↗
PubMed2000

Thyroid surgery and voice-related outcomes.

BACKGROUND: Vocal dysfunction in patients with thyroid pathology has been poorly documented, and dysfunction after thyroid surgery is generally reported in terms of recurrent laryngeal nerve or external laryngeal nerve palsy. But voice dysfunction is more complex than simply nerve integrity. The present study reports the incidence of dysphonia in patients presenting for thyroid surgery, and relates postoperative changes in vocal function to recurrent and external laryngeal nerve function, and the surgical handling of the strap muscles. METHODS: Fifty patients were assessed by Visipitch before and after thyroidectomy. Following surgery the patients filled out a questionnaire. RESULTS: Overall 26 of 44 patients had no subjective postoperative voice change, while 10 reported subjective deterioration and eight reported subjective improvement in voicing. Postoperative objective assessment of these patients found that 17 were the same, eight refused to come for testing because they felt their voice had not changed, 13 were better and six were worse. Following surgery two patients (4.5%) had temporary recurrent laryngeal nerve palsies (2.5% of nerves at risk), and four patients (10%) suffered external laryngeal nerve palsies. Division of strap muscles was not detrimental to voicing. Six patients were lost to follow-up. Fifteen patients (34%) presented with vocal abnormalities, six (40%) of whom improved postoperatively. CONCLUSIONS: Patients may have voicing abnormalities before thyroid surgery is performed. Surgery may improve or worsen the voice irrespective of the pre-operative voice status.

Adult↗